Mina had saved two envelopes for the reunion. A note on the red one promised a photograph today. The blue one promised a whole album next year. Mina hoped the album would entice someone to wait. (entice: tempt, lure, attract) She expected her old economics class to recognize delayed gratification. (delayed gratification: deferred gratification, postponement of gratification, deferred reward) Instead, her most impulsive classmate asked whether he would still live at this address in a year. (impulsive: impetuous, rash, spontaneous) Mina had done her analysis on paper. (analysis: examination, study, investigation) This was one ramification of a long wait that she had overlooked. (ramification: consequence, implication, repercussion)
Her former teacher drew an intertemporal choice on a napkin. (intertemporal: in this context cross-period, across-time) In the familiar framework of discounted utility, timing changed the value assigned to each reward. (framework: structure, scaffold, skeleton; discounted utility: in this context time-discounted utility, discounted satisfaction) Exponential discounting applied the same proportional reduction for each additional year. (exponential discounting: alternate name constant-rate discounting, geometric discounting) Time consistency meant that merely moving closer to the date need not reverse a preference. (time consistency: intertemporal consistency, consistency over time) He tapped his neat diagram. "Now ask me again when the red envelope is in my hand."
Mina did. He chose the photograph, admitted a present-biased preference for the immediate pleasure, and laughed at his own inconsistency. (present-biased: in this context immediacy-favoring, weighted toward the present; inconsistency: contradiction, discrepancy, incongruity) The girl in the photograph was his wife, long before they had met. He passed it around. Every student who had chosen the album quietly thanked the man who hadn't.